The present invention relates to the production of liquid hydrocarbons and more particularly to the production of liquid hydrocarbons using in various thermal methods.
In recent years, as a result of decreasing reserves and increasing prices, the use of various thermal methods to produce heavy crude deposits has become economically attractive. In the most common thermal recovery process steam is injected by means of a well into the heavy crude deposit to reduce the viscosity thereof and allow the crude to be produced. Various methods have been used in thermal recovery, for example, in one method the steam is injected and the formation is allowed to soak and the crude drains into the well from which it is subsequently produced. In another method steam is used to drive the crude from one well toward another well. In all these cases it is desirable to know the injection profile of the steam entering the formation through the perforations in the well casing. Also, it is desirable to know the quality of the steam actually entering the formation so that the BTU input to the formation can be determined. The efficiency of the recovery can be calculated and steps taken to improve that efficiency.
The above referenced patent describes a method by which the quality of the steam entering a formation may be measured. The apparatus includes a wire bristle arrangement which is used to separate the liquid from the vapor in the steam and permit the measurement of the quantity of liquid separately from the vapor. This permits one to determine the actual quality of the steam at the point of injection. Also, the apparatus can be used to determine the quality of steam at various depths in the wellbore and thus the actual profile of the steam quality can be accurately measured.
The '627 patent relies upon a wire bristle arrangement in which the bristles bear against the inner wall of the well casing to separate the water from the vapor and funnel the water toward the center of the apparatus. The patent discloses a bristle arrangement in which individual wire bristles are clamped to a mandrel arrangement to provide an arrangement in which the bristles project radially outward from the mandrel. The overall diameter of the bristle arrangement is larger than the diameter of the well casing so that as the bristle arrangement is lowered into the well casing the bristles will bend upwardly and thus funnel the liquid that is separated from the vapor toward the center of the instrument. The bristles are deformed into a cusped-shaped convex upward as the tool is lowered into the well. Conversely, as the tool is pulled up the casing, the bristles invert and form an umbrella-shaped region convex downward. As vapor and liquid flow through the bristles, the drag force caused by fluid flow depends on the vapor and liquid flow rates and upon whether the bristles are pointing "up" or "down." In the former case, total drag depends more strongly on liquid flow rate, since the liquid path is more drastically altered.
The '627 patent discloses the use of braided stainless wire for forming the individual bristles. The individual bristles are attached by either welding their inner ends to the mandrel or clamping them to the mandrel by suitable means. As explained in the patent, the use of welding to attach the bristles to the mandrel or central assembly of the tool is not desirable since the heat of welding affects the mechanical properties of the bristles and reduces their effectiveness. While clamping overcomes the effects of welding, it does pose a problem in distributing the bristles in a uniform arrangement around the mandrel. The multiple rows of bristles also require a complicated clamping arrangement to properly space the individual rows of bristles and provide a uniform bristle arrangement that will separate all of the liquid from the vapor.
Accordingly, the present invention is directed to overcoming these and other problems experienced by the prior art.